Add Checked DetailsView Rows to a new DataTable

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

public partial class joblist : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[2] { new DataColumn("CompanyName"), new DataColumn("Designation") });
dt.Rows.Add("NIIT", "programmer");
dt.Rows.Add("annvision", "Webdesigner");
dt.Rows.Add("softtech", "designer");
dt.Rows.Add("Mahad", "Programmer");
DetailsView1.DataSource = dt;
DetailsView1.DataBind();
}

}
protected void Button1_Click(object sender, EventArgs e)
{
Response.Redirect("~/secure.aspx");
}
protected void Page_PreRender(object sender, EventArgs e)
{
if (GridView1.SelectedRow == null)
{
DetailsView1.Visible = false;
}
else
{
DetailsView1.Visible = true;
}
}

protected void Apply_Click(object sender, EventArgs e)
{
Response.Write("You are successfully applied");

DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[2] { new DataColumn("CompanyName"), new DataColumn("Designation") });
foreach (DetailsViewRow row in DetailsView1.Rows)
{
if (row.RowType == DataControlRowType.DataRow)
{
CheckBox chkRow = (row.Cells[0].FindControl("chkRow") as CheckBox);
if (chkRow.Checked)
{
string CompanyName = row.Cells[1].Text;
string Designation = (row.Cells[2].FindControl("lblDesignation") as Label).Text;
dt.Rows.Add(CompanyName, Designation);
}
}
}
GridView2.DataSource = dt;
GridView2.DataBind();

}


}
it showing error near detailview1.DataBind();